Thanks for all your replies.
That's very thorough little test harness there Browser, nice. I think your going to beat me when you see that the nub of the question was just all about return values. This finally works 
#!/usr/bin/perl


dofistcritical() or dobackupcritical() or dofailed();


sub dofistcritical {if (int rand 5)
    {print "hooray it worked first time!\n"}
    else {return 0}}

sub dobackupcritical {if (int rand 5)
    {print "First time failed but luckily the backup worked...phew\n"}
    else {return 0}}

sub dofailed {if (int rand 5)
    {print "Main failed. Backup Failed. You have 3 minutes to reach a 
+safe distance\n"}
    else {return 0}}

[download]
I'm not exactly sure where it was failing before, but the complicated blocks to force critical and non-critical areas must have had me seeing things, from here I can work the critical/non-critical sections back in.
Cheers all.

In reply to Re: Nested OR as a control structure by andyf
in thread Nested OR as a control structure by andyf

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.